But it would, de Boer says, overcome the obstacle that is preventing a global deal being signed – the countries simply don't know what they are signing up for.

They don't know what to expect in terms of the "rules and tools" that will govern measures to cut carbon emissions, to adapt to global warming and to pay for it all.

De Boer, now looking far more relaxed in his new role with accounting giant KPMG than he was in the fraught days of Copenhagen and Bali, remains adamant that Copenhagen was a success, but does acknowledge that views on that differ very widely.

He also says that lots of the political momentum that was there in the runup to Copenhagen, attended by 130 or so world leaders, is still there. I think we can agree de Boer is an optimist, to say the very least.

He remains, as befits his new business-oriented job, certain that a global cap and trade scheme – a "market-based mechanism" – is the ultimate solution to cutting greenhouse gas emissions and limiting global warming.

And it is here that a glimpse of anxiety can be seen: "I just hope they hurry up and define what exactly those market-based mechanisms will mean, as they will need to continue after 2012 [when the current Kyoto agreement ends] ... 2012 is getting frighteningly close."

He also used some colourful language when addressing the lobbying by certain fossil fuel interests. If I was a more ruthless kind of journalist, I could tell you de Boer said fossil fuel companies were living in the stone age. I'm not, but the full quote is still fun.

"I do not think oil, gas and coal companies are evil. They are selling products that we as consumers want. The question is how to balance that with the needs of the environment. There will always be winners and losers [during change]. When the massive economic transformation from the stone age to the bronze age took place, I am sure that stone spearhead makers were pretty upset."